Diagnostic Aids
WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Intake Air Temperature (IAT1) sensor, located inside the mass air flow housing, is a thermistor-type sensor with a variable resistance that changes when exposed to different temperatures. When interfaced with the Powertrain Control Module (PCM), it produces a 0-5 volt analog signal that will measure temperature. The IAT1 sensor's primary function is to measure intake air temperature to control timing and fuel rate when cold starting. Continuous monitoring by the IAT1 sensor limits smoke emission.
An IAT signal that is detected out of range high or low by the PCM will cause the engine to ignore the IAT signal, and assume an ambient temperature of 77°F (25°C). This test is intended to diagnose the following components and circuits:
- Intake Air Temperature (IAT) Sensor
- Wiring Harness Circuits; (IAT & SIG RTN)
- Powertrain Control Module (PCM)
IAT SENSOR SPECIFICATIONS
| Temperature - °F (°C) | Resistance - k/Ohms | Volts |
|---|---|---|
| 248 (120) | 1.19 | .28 |
| 230 (110) | 1.56 | .36 |
| 212 (100) | 2.08 | .47 |
| 194 (90) | 2.80 | .61 |
| 176 (80) | 3.84 | .80 |
| 158 (70) | 5.34 | 1.04 |
| 140 (60) | 7.55 | 1.34 |
| 122 (50) | 10.93 | 1.72 |
| 104 (40) | 16.11 | 2.15 |
| 86 (30) | 24.25 | 2.63 |
| 68 (20) | 37.34 | 3.09 |
| 50 (10) | 58.99 | 3.52 |